Fomos Foster 8 L or 12 L: choose by chamber dimensions, instrument length and permitted load
- 15 min reading time
To choose between the Fomos Foster 8-litre autoclave and the Fomos Foster 12-litre autoclave, start with the longest instrument, the external dimensions of its permitted sterilisation packaging, and the load configuration authorised by the manufacturer. The 12-litre model offers a wider chamber and a greater listed depth, but twelve litres does not mean fifty per cent more usable instrument sets. The 8-litre model may be entirely appropriate when the actual instruments and their permitted arrangements fit.
Prohaar currently lists two active white Foster machines with built-in printers: 8 litres, SKU 154444 and 12 litres, SKU 154445. Both current product cards list a thermal printer, USB recording, three trays, five sterilisation programmes and two test programmes. The decision is therefore mainly about the usable geometry and accepted load, not about which model supposedly has more programmes. Every instrument, package and selected cycle still needs to meet the relevant instructions for the exact machine delivered.
The 8-litre listing gives a chamber of Ø 170 × 320 mm. The 12-litre listing gives Ø 200 × 350 mm, whereas a previous review of the original Foster 8L/12L manual identified revision 202401A with Ø 200 × 358 mm for the larger model. Do not treat the additional eight millimetres as guaranteed usable space. Fomos lists a Foster 8L/12L user manual; confirm the applicable revision against the serial number and documents supplied with the unit before buying for a critical dimension.
1. Begin with your instruments, not with the litre figure
Make an inventory of the reusable instruments the business actually processes. Distinguish individual metal tools, hinged instruments, removable parts, protective holders, and pre-assembled sets. For each item, find the instrument manufacturer's processing instructions: is steam sterilisation permitted, is disassembly required, which preparation is acceptable, and what packaging can be used? A larger steriliser cannot make a heat-sensitive or moisture-sensitive item compatible with steam. The autoclave product page cannot override the instructions supplied for the instrument itself.
Measure the longest item in the configuration in which it is permitted to be processed. A hinged instrument may require an open position that takes more space than its closed length. A cassette may determine the real footprint of a whole set. When an item is packed, the outer dimensions of the final approved pouch or container matter more than the bare metal tool. Do not assume that a pouch may be bent, compressed against the door or stacked without clearance simply because the object fits inside a cylindrical chamber.
The result should be a short, specific inventory of critical lengths, widths, materials and wrapping methods. If your largest permitted package can be positioned correctly on the 8-litre tray, and the programme's load limits allow it, the smaller device may suit the business. If the limiting factor is width or length, examine the 12-litre model. That is a conditional comparison, not an approval to pack the larger chamber to the wall or to exceed any programme restrictions.
2. Compare the dimensions and included features accurately
| Item to verify | Foster 8 L | Foster 12 L |
|---|---|---|
| Prohaar SKU | 154444 | 154445 |
| Nominal volume | 8 litres | 12 litres |
| Chamber diameter | Ø 170 mm | Ø 200 mm |
| Depth in current shop listing | 320 mm | 350 mm |
| Depth noted in earlier manual review, revision 202401A | 320 mm | 358 mm; check current revision |
| Trays in listed package | Three | Three |
| Cycle recording | Thermal printer and USB listed | Thermal printer and USB listed |
| Programmes in product card | Five sterilisation; two tests | Five sterilisation; two tests |
The larger model has a listed diameter thirty millimetres greater. This can matter for a wide package, but a round chamber is not a rectangular shelf that offers its full diameter everywhere. The tray frame, curved wall, packaging and the manufacturer's spacing requirements restrict the position that can actually be used. Likewise, the stated chamber depth is not the maximum allowable length of a wrapped instrument. A door mechanism or the position required by the tray can make a nominally possible item inappropriate for the authorised arrangement.
The current product cards show tray dimensions as 26 × 12.5 × 1.5 mm for the 8-litre version and 26 × 14.5 × 1.5 mm for the 12-litre version. Those units appear implausible for the described trays. We do not silently replace millimetres with centimetres: the proper tray measurements need confirmation in authoritative documentation or by the supplier. This is a specification discrepancy, not permission to invent a more convenient figure or to design a loading pattern from an obvious-looking typo.
3. Why chamber capacity cannot be converted into a number of sets
Eight or twelve litres describes nominal internal capacity, not a tested number of wrapped salon sets. A set occupies more than the sum of its instruments' solid volumes: the packaging has thickness, width, orientation and a surface that must be accessible to the process. A cassette uses space with its protective structure. Dense metal loads and porous items may be subject to different limitations. The cycle and the manufacturer, rather than a simple volume division, determine which types and masses of load are allowed.
That is why a claim such as 'eight sets per 8-litre cycle' or 'twelve sets per 12-litre cycle' would be misleading without a precisely defined set. The same salon might use narrow single-item pouches for one treatment and a broad rigid cassette for another. Two packages of equal length can behave quite differently because of their material, metal mass and permitted orientation. The larger chamber may ease positioning but does not prove that the extra nominal litres may be filled with instruments at will.
Before purchasing, draw a plan of a representative permitted load or ask the supplier to check it against the exact model instructions. Record the item and its manufacturer's conditions, the packaging outside measurements, the tray it will occupy and the selected authorised programme. 'Physically fits' and 'is a permitted, validated configuration' are different statements. Neither the shop's litre figure nor a photograph of a full tray can replace that check.
4. A Class B model can still have programmes labelled Class S
Both Foster listings describe Class B autoclaves. However, their programme tables also identify quick cycles as Class S. A purchasing decision must therefore distinguish the machine's marketed category from the classification and permitted uses of the programme selected for a particular load. Do not infer from the Class B wording on the product title that every button is appropriate for wrapped, hollow or porous materials. Follow the model-specific manual and the instrument and packaging manufacturers' instructions.
The five sterilisation and two test programmes stated in both shop listings are reported features. They are not independent validation for your exact instrument set. Preparation, loading, steam exposure, drying and applicable monitoring must form a coherent process. The printer can create a record of a run, and USB can support digital storage, but the presence of a printed trace alone cannot establish that every item was properly cleaned, packaged, loaded or assessed.
The CDC Sterilizing Practices guidance discusses proper preparation, packaging, circulation, selection of appropriate cycles and monitoring. Its scope is US healthcare facilities. We use it as technical background to explain why physical fit is insufficient, not as Dutch salon law or a US approval transferred to this product. Local obligations and operating procedures require a separate assessment for the relevant jurisdiction and professional activity.
5. Three realistic buying situations without invented throughput
First, imagine a small practice using mainly short reusable metal instruments for which the manufacturers permit steam treatment. When the completed packages fit on the 8-litre trays with the authorised clearance and the accepted load and cycle requirements are satisfied, the 8-litre Foster may be sensible. The 12-litre version does not automatically produce a more sterile result. Any later decision to move up would depend on a changed instrument list or loading needs, not a general promise about better hygiene from additional volume.
Second, a practice may have a long instrument, a larger cassette or wide protective packaging that does not fit correctly in the 8-litre usable arrangement. Here the additional listed diameter and depth of the 12-litre model are relevant. Nevertheless, the final package must fit the actual trays and be acceptable for the selected programme. Do not use the contested 358 mm depth as a guaranteed pouch length, and do not compress packaging or remove protective components merely to fit a chamber.
Third, a busy salon may have many instruments per day but several incompatible packaging or material groups. Total daily quantity alone does not settle 8 versus 12 litres. Map the actual load types and the corresponding permitted programmes, then examine whether the larger chamber offers usable value. A second device, different scheduling or a change of instruments might be considered, but this article does not invent the number of cycles per hour, daily capacity or financial return without verified practice-specific information.
6. Allow for the machine footprint and receiving checks
Chamber dimensions are internal. Operating space includes the machine, its door swing, the necessary clearances and access for electricity and water. The two current shop cards both list external dimensions of 560 × 408 × 420 mm and packed dimensions of 710 × 550 × 525 mm. These are current catalogue entries, not our own measurements. Identical listed measurements in two descriptions are not proof that the outside of every variant is identical. Confirm the installation dimensions and manufacturer's clearance requirements against the manual supplied with the specific model.
The current listed contents include the autoclave, a frame with three trays, tray removal handle, thermal paper, drain hose, power lead, door gasket, user manual and technical sheet. Use that list as a receiving checklist. Check the SKU, the actual variant, manuals and accessories before the workplace is built around the instrument. A missing or mismatched part should be resolved with the supplier; substituting an unapproved component is not an acceptable way of making a unit 'ready'.
Both listings state that the autoclaves are to be operated by appropriately qualified and trained personnel. An equipment plan must also consider where used and prepared instruments are handled, where approved packaging is kept, and how processed items are stored. Extra chamber space does not solve problems of workflow separation or staff training. These are practical planning questions, not promises that the larger machine is automatically safer.
7. The 20.5 cm and 23 cm door seals are model-specific parts
The shop lists a silicone door gasket for Foster 8 L, SKU 154448 with an outer diameter of 20.5 cm. It separately lists a silicone door gasket for Foster 12 L, SKU 154449 with an outer diameter of 23 cm. The product descriptions explicitly assign them to different models. This is helpful when deciding which spare parts may need to be identified in purchasing records or when reviewing long-term access to the correct model's components.
These measurements describe the outer size of the door gaskets, not the sterilisation chamber diameter. They cannot be used to infer the size of an allowed load. Do not assume interchangeability because both seals are silicone and both machines carry the Foster name. Check the machine's exact version and original service documentation; installation, replacement and subsequent checks must follow the applicable manufacturer procedure. This comparison is not a repair tutorial.
8. Evidence boundaries: store cards, manual revisions and actual loads
There are three distinct kinds of evidence. Current catalogue facts establish which models and functions Prohaar offers and what its pages state today. Manufacturer documentation determines the intended operating conditions for a given revision, including accepted loads and programmes. Your practice's evidence includes the instrument manufacturers' instructions, the actual packaging sizes and how the intended arrangement is assessed. No one of these sources can independently establish a valid cycle for every possible salon instrument.
The original Foster manual, revision 202401A, gives a Ø 200 × 358 mm chamber for 12 litres; the current store card lists Ø 200 × 350 mm. This is a discrepancy between two identified sources, not extra space available to use at will. Match the offered unit’s revision and serial number to its supplied documentation and confirm usable tray dimensions. Neither depth automatically defines the maximum permitted package length.
9. A practical purchasing worksheet
Begin with the instrument register: item identifier, manufacturer, steam compatibility, required preparation and permitted packaging. Add the outside measurements of each complete pouch, tray or cassette. Then check the actual supplied tray dimensions and chamber arrangements for both candidate models. Identify the authorised programme and its load limits in the applicable device manual, including any restrictions on packaging type and mass. Keep these fields separate: nominal chamber volume, inside dimensions, usable tray positions and validated permissible load are four different things.
The 8-litre machine is a candidate when those complete packages demonstrably fit within its permitted configuration. The 12-litre version is worth considering when width, length or allowable positioning is the bottleneck. If a few millimetres determine the purchase, settle the difference between the listed 350 and previously recorded 358 mm before ordering. Also clarify the tray units rather than calculating with an uncertain source line. Where instrument compatibility or permitted load details remain unknown, make the decision conditional, not more confident.
Compare the current Foster 8 L and Foster 12 L, and Prohaar autoclaves collection. Each can help identify the offered configuration, but a listing is not a universal authorisation for every tool, pouch or cycle.
Frequently asked questions
Is twelve litres always better than eight litres?
No. More nominal volume provides more physical space, but does not prove a larger permitted mass, a fixed set count or better processing. The 8-litre model may be sufficient if complete instrument packages fit and the selected programme and load limits permit them. The authorised load, rather than the litre label alone, decides.
What are the chamber dimensions of Foster 8 L and 12 L?
Prohaar currently lists Ø 170 mm by 320 mm for 8 L and Ø 200 mm by 350 mm for 12 L. A previous review of manual revision 202401A noted 358 mm for the 12-litre depth. Check the supplied manual before relying on the disputed dimension.
Can I use the chamber depth as the maximum package length?
No. The round chamber, tray, door, positioning and required circulation must be considered. The device and packaging manufacturers' instructions establish what configuration is permissible; chamber depth alone does not.
How many metal nail tools can one Foster cycle hold?
No fixed number can be given without identifying the tools, their mass and outer packaging dimensions, the tray position and the accepted programme. A litre-based number would be an invented performance promise.
Are all cycles on these Class B autoclaves Class B cycles?
Do not assume so. The product tables also describe quick Class S programmes. The actual selected programme and the permitted load type must match the current original instructions.
Does the printer prove that every processed item is sterile?
A printout records aspects of the machine cycle. It does not, on its own, prove correct prior cleaning, packaging, loading or monitoring for every item. USB is a recording feature rather than a stand-alone validation method.
Are the 8 L and 12 L door seals interchangeable?
The current cards list separate parts: the 8 L seal, SKU 154448, with a 20.5 cm outer diameter and the 12 L seal, SKU 154449, with a 23 cm outer diameter. Select and service them according to the exact model documentation.
Prohaar Magazine editorial team · Current product information and accessible sources checked on 14 October 2026. Use the manufacturer instructions applicable to the delivered unit for programme and load decisions. Primary reference: Fomos Foster 8L/12L user manual; background: CDC Sterilizing Practices (US healthcare context, not Dutch salon law).
Buying decision: consider the Foster 8 L if your real permitted packages and load fit. Investigate the Foster 12 L when width or depth is the limitation. Confirm package length, usable tray dimensions, accepted load and the applicable manual revision before ordering, without guessing how many sets fit.